Currently, it is an international phenomenon that an owner of a mobile phone carries with him his mobile phone when he travels. This can be ascribed mainly to convenience, and partly to the availability of roaming service provided by phone service providers.
When a person makes a call through his own mobile phone in, for example, a foreign country, he uses the roaming service provided by his home mobile phone service provider (and its partners). Roaming service automatically allows the mobile phone owner to be reached by calls made from (or routed through) his home country, and also allows the mobile phone owner to make calls out of the host country to anywhere in the world through the home mobile service provider. Roaming service includes features such as auto-detection of the traveller's location and the nearest local host phone service partner of the home mobile service provider in order to bridge the communication (e.g. auto-roaming etc.). Unfortunately, mobile phone roaming service is very expensive.
Any call through a roaming service in a foreign country reaches the home mobile service provider of the phone before it is re-directed to the destination. For example, if a traveller to the UK makes a call in the UK through a Singapore mobile phone to a destination which is also in the UK, the connection has to be directed from UK to Singapore before it is re-directed to the UK again. An expensive round the world connection is made.
Furthermore, in some countries, even calls made to destinations within a same country using local phones are made through roaming connections. For example, inter-states mobile phone calls within the USA or India may be charged roaming service rates.
FIG. 2 illustrates an example of a known telephone system. A traveller brings his phone 24 which is registered for use in country A 21. By sending a roaming SMS 22 when the traveller is in country B 25, the traveller indicates to the owner the destination phone 26 who receives the SMS, who is in country A 21, to call him by way of an inbound call 23 through the traveller's roaming connection. In this manner, the traveller avoids an outward roaming call from country B 25.
Referring now to FIG. 3 which shows another prior art known as SMS Callback, a resident (not shown) in country B 35 has bought a phone 34 which is registered for use in country B 35. The resident then also registers the phone with a gateway provider, not shown, of the embodiment which provides cheap SMS callback connection. The gateway provider may or may not be installed in the same country as a gateway 37 it provides, the dotted line depicting the possibility of the gateway 37 being linked to a gateway provider in another country A 31. The resident sends 32 an SMS from country B 35 to a gateway 37 of the gateway provider using his mobile 34. The gateway 37 then performs a callback 33 to the mobile phone 34 of the resident, as well as a call out 38 from the gateway to a destination phone 36 in the same country B 35. The two calls 33, 38 are patched 39 at the gateway 37 when the connections are successful and the two phones 34, 36 are thus connected for conversation. In a variation of this prior art, the destination phone 36 may be of another country, or registered in a different country from the country in which the resident's mobile phone 34 is registered. The gateway 37, like the gateway provider itself, may either be situated in a different country, e.g. country A 31, or in the resident's country B 35. The calls placed by the gateway may therefore either be long distance calls from country A 31 or local calls in country B 35.
The prior art is limited in that it does not allow a traveller who frequently travels to different countries to avail himself of the advantage of a callback connection through local operators in every foreign country. The task of buying phones (or SIM cards) registered for local operation in different countries and to record the different numbers of the phones will be daunting even to the most well organised traveller. In addition, some countries have telecommunication monopolies which prevent the use of SMS callback initiated from servers or gateway stationed within the country.